9 ms·
Actually, it's not SMD components in particular. The failure mode for many MOSFETs and other semiconductor devices tends to be a short. They only tend to fail
by _wiv7 8y ago
Actually, it's not SMD components in particular. The failure mode for many MOSFETs and other semiconductor devices tends to be a short. They only tend to fail open if there was enough energy at hand to blow the short clear.
- dmoy 8y agoAh yes, I remember from lab, you'd get a fail open right after you managed to manufacture a temporarily light emitting diode from things that are not normally light emitting diodes (or maybe not even diodes).
- bsder 8y agoWe call those "Light Emitting Resistors". They result when you attempt to violate Ohm's Law. You can generally diagnose those olfactorily as well as visually. :)
- morganvachon 8y ago> You can generally diagnose those olfactorily as well as visually. :) Indeed, my electronics engineering mentor described it as "letting the magic smoke escape". Once the smoke is gone, so is the magic.
- lathiat 8y agoNow if only you could capture the smoke and get it back inside the chip. It would work again!
- MisterTea 8y ago> exercise Ohm's Law. FTFY ;-)
- phyzome 8y agoOr alternatively, SEDs (smoke emitting diodes).
- tyingq 8y agoOld bad electrolytic capacitors often smell like bad fish. Not sure why.
- Yetanfou 8y agoThere was this guy called Edison who once made quite a healthy business out of selling LERs. They seem to have lost some of their sheen nowadays but I suspect they'll make a come-back one day in miniaturised form, something like 'nano-LERs'.
- marshray 8y agoEverything's a fuse, it's just a question of how much current it takes to blow.
- crankylinuxuser 8y agoIndeed! Reminds me of this joke image https://i.imgur.com/TtFotWu.jpg https://i.imgur.com/TtFotWu.jpg Unfortunately, in really old houses, I have seen pennies used. Shudder
- mchahn 8y agoI had a friend that would fix bad PCBs that had a short in a middle layer by hooking up a car battery and burning up the short. It actually worked.
- marshray 8y agoThese days I bet a thermal camera would be great for finding those.
- watersb 8y agoRossman (see link above) shows how to use 91% isopropyl alcohol to find these more effectively. It evaporates more rapidly at the heat source, so there's your short. I don't know how well this would work to find shorts in middle layers of circuit boards; I am still learning to identify the broken active components on the surface.
- sebazzz 8y agoIt worked without unwanted side-effects? Wow.